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The Most Important Developments in Spraying

By Tom Wolf

Some years ago, a few of us weed scientists sat around a table and debated the most important agricultural developments in our lifetimes. It was a great discussion, and we arrived at a few that included direct seeding, for its soil and moisture conservation as well as improved fertilizer placement, GMO crops, for slowing Group 1 and 2 herbicide resistance and the abandonment of summerfallow in much of Western Canada. Let’s apply this exercise to spray application to see what we come up with.

What follows is my version of the most important spray technology developments in the last 50 years.

1. Low-drift nozzles: Spray drift is the biggest time management challenge and also perhaps the biggest public relations battle. These nozzles reduce drift, making more time available for safe and effective spraying.

2. Rate controllers: On the one hand, a rate controller matches sprayer output to travel speed. On the other, it has allowed spray pressures to go wherever they need, even beyond the optimum, to match travel speed, and that can lead to nozzle performance issues.

3. Pulse width modulation: The pulsing nozzle fixes the rate controller problem mentioned above. Now, travel speed and pressure are independent. Plus, a whole host of other flow management options become available such as turn compensation.

4. Optical spot spraying: Once you see these in action, you can’t go back. Why would you spray a whole field when weeds only cover 10 per cent of it? Products like WEEDit and WeedSeeker are proven green-on-brown performers after years of field success around the world. 

5. GPS guidance: Some of us grew up with foam or disk markers, others learned to aim for brave family members perched on headlands. Achieving accuracy was stressful. The importance of this development is probably underestimated.

6. Sectional control: The ability to adjust the spray width in individual nozzle steps makes sense. In fact, that alone can save five per cent of an annual chemical bill compared to conventional sections measuring about 10 to 15 feet. And it’s definitely better than the left boom or right boom options from the 70’s and ‘80s.

7. Operator comfort and safety: The refuge of the cab makes longer days bearable for all equipment, but for spraying it dramatically improves safety as well.

Now that we covered off what is right, it’s time we take a look from a different perspective.

But we’re far from done. We still need work in these areas:

1. Cleaning and waste management: I can’t imagine another industry where managing potentially hazardous leftover materials are left to the discretion and circumstances of the applicator. Let’s make it easy and fast to thoroughly clean the sprayer and safely dispose of leftovers so we can shout it from the mountaintops.

2. Boom stability: Booms are too high, resulting in more drift and poorer nozzle performance, adding to operator stress. The sole reason is unsatisfactory levelling. It’s possible to solve this. 

3. Weight: The road to productivity seems to be paved with larger, heavier machines. The side effect is fuel consumption, compaction and getting stuck. Let’s get smarter with frame design and logistics and talk acres per hour rather than tank capacity and power.

4. Cost: All farm equipment has seen cost increases that far outstrip inflation or any reasonable accounting of productivity and features. Sprayers lead the way.

5. Drift management. Sprayer design continues to ignore drift management. We need sprayers that produce less drift by design, and this requires consideration of tractor unit, wheel and boom aerodynamics.

A few areas show promise and may suit certain niches:

1. In-crop weed sensing: The green-on-green sensing that has been made possible by machine learning has shown encouraging early success. Continual improvements will eventually bring its reliability to within commercially acceptable standards. There is significant activity below the radar in this area, as all players recognize the enormous upside of a breakthrough.

2. Autonomy: While dispensing a pesticide adjacent to sensitive areas isn’t exactly the low-hanging fruit of autonomy, such field sprayers will have a fit in the temperate plains of North and South America, Australia and Asia.

3. Drone application: The rapid pace of advancement in remotely piloted aerial systems, along with a seemingly low barrier to entry of new companies, will put pressure on the industry to make a decision on this alternate application method. If it can be done safely, it will have a dramatic impact.

Don’t ignore the small things you can do in your operation. Although we’re conditioned to look for game-changing technology, the most sustained improvements don’t come from a single innovation, but from a period of persistent evolution. Spray application is no different.